This invention generally relates to signalling devices and especially to signalling devices that are useful in public transportation vehicles.
Buses and other transportation vehicles generally have a signalling device that enables a passenger to notify the driver when the passenger wishes to leave the vehicle. In a bus, for example, the passenger signals the driver by pulling on a cord that runs along the wall of the bus above the seats. On most buses, pulling the cord closes a switch thereby to energize or complete a circuit from the electrical supply of the bus through a vibrator, or buzzer. The buzzer converts the electrical energy into an audio signal. In many situations, this is an effective procedure for notifying the driver.
In other situations, however, it is not. Many times mischievous persons or vandals may ride the bus. Such persons will pull the cord and not release it. With present signalling devices, the driver has only two alternatives. He can leave the buzzer on and thereby subject both the passengers and himself to the noise. Alternately, he can turn the signalling device completely off. However, if the driver forgets to turn the signalling device back on, a passenger can pull the cord without any response. This then becomes a source of further annoyance to the passengers.
One approach to solving this problem has been to substitute a "chime" signalling device for the conventional device. This does tend to alleviate the problem of vandals. However, the installation of such a device usually is a complete substitution of the new device. Such an alternative then increases the overall costs of the bus.
Moreover, it also has been proposed to use various electromechanical controls for controlling an audio signalling device. In one such approach, described in U.S. Pat. No. 3,792,468, a passenger pulls the cord that closes a switch simultaneously to energize the audio signal and a thermal delay switch. At the end of a delay established by thermal delay switch or upon release of the cord, whichever comes first, the audio signal turns off. Thereafter the circuit is disabled until a door is opened by the driver, whereupon the circuit is reset.
This approach does not prevent repeated energization of the audio device by repeated pulling of the cord until the thermal delay interval expires. Also, the control requires the installation of special switches at the exit doors or on the driver's door control switch thereby complicating the installation of the control. Further, electro-mechanical relays of the type required for this application must be rugged and insensitive to the environment. Such relays tend to be large and expensive.
Therefore, it is an object of this invention to provide a novel controller for existing signalling devices on a bus or other public transportation vehicle.
Another object of this invention is to provide a controller that is adapted for use with the existing signalling devices and that is inexpensive to use and install.
Still another object of this is to provide a controller that is small.